1. Field of the Invention
The present invention relates to a waste treatment system, and more particularly to a waste treatment system for treatment of organic waste and digested liquid of the organic waste.
2. Description of the Background Art
A technique for treating organic waste and recovering electric energy and thermal energy during the treatment has conventionally been disclosed (e.g., in Japanese Patent Laying-Open No. 2002-151131). With this technique, organic waste is subjected to anaerobic fermentation to obtain methane gas. The digested sludge is then dewatered and converted into a low molecular weight substance to also obtain methane gas. The methane gas thus obtained is used as fuel for a fuel cell.
The digested liquid from the anaerobic fermentation described above, however, requires removal of nitrogen upon effluent disposal. If the removal of nitrogen is to be conducted by microbial treatment, a large amount of methanol is necessary as hydrogen donor, and a polymer flocculant and a large-scale processing bath are also required, leading to an increased cost. The organic waste treatment also needs removal of phosphorus, which requires an additional cost of introducing a chemical agent or the like, and also requires complicated processing for adjusting pH.